Insulating pipe covering



Patented June 17, 1952 INSULATING PIPE COVERING COMPOSITION HaroldKarren Thomas, Phoenix, Aria.

No Drawing. Application October 23, 1950, Serial No. 191,723

4 Claims. (Cl. 106-84) This invention pertains to insulating pipecovering composition, and is a continuation in part of my application,Serial Number 162,542, filed July 21, [947, now abandoned.

One of the objects of the invention is to provide an insulatingcomposition in which granular sintered and expanded perlite is theprincipal ingredient, and in which an inorganic binder is used tosupplement the natural tendency of certain perlite granules to cake whencompressed;

Another object is to provide an insulating pipe covering composition ofperlite granules, an inorganic binder, and a binder setting agent whichcan be handled as a dry mix and pressed to the shape desired andimmediately applied to the P p Another object is to provide aninsulating pipe covering which has a firm texture, is water re sistant,and will afiord a maximum degree of insulation at a minimum cost.

I attain the foregoing objects by means of the mixture, the compositionof matter and the practice hereinafter described.

vermiculite, pumice, and perlite having horny projections and cavernousvugs are each entirely unsuited to the purposes here concerned.Particles of the proper type, when pressed together, knit or clingtogether and form a solid cake, even with slight compressive pressure.This is thought to be due to partial crushing of adjacent cell walls.The edges of cells remaining after crushing become included within theedges of opposite cells and the whole mass shrinks in volume, becomesmore dense and clings together. The volume shrinks in proportion to thepressure applied. Knitting commences when a sufllcient number or cellshave been mutually compressed. A compacted mass or this type of perlitemay be compressed to about one-third its original volume and theparticles, partially crushed, dry, and without any binder, will knit,and form a cake which may be handled and moved without break- To secureusable objects of compressed perlite, oi firmer texture and with lesspressure, than would be the case if dry granules were compressed, I mixperlite granules with sodium silicate as a binder, then add sodiumchloride, preferably in the form of finely ground rock salt as a settingagent and subject the mass in moulds to a compression pressure of about5 to '7 tons per square foot. Insulating shapes thus formed may beapplied at once to pipes or boilers without drying. When dried thesecoverings have a greater compressive strength than commercial pipecoverings now in common use.

out breaking. Quick To form insulating semi-cylindrical pipe coveringsections 1 select perlite granules oi. the above mentioned type,composed of thin walled bulbous cells, in a plaster grade aggregate. Thegranules and particles composing this aggregate are substantially of thefollowing sizes:

Preferably, the aggregate weighs from 4 to 10 pounds per cubic foot.

The mixture is then prepared in following proportions:

To one cubic foot oi the above specified aggregate 1 add with continuousmixing, approximately one half gallon, liquid measure, of sodiumsilicate, 40 Baum as a binder.

After the particles of this mix have become coated with the binder, Iadd as a setting agent approximately ten ounces, avoirdupois, of sodiumchloride in the form of finely ground rock salt, and continue mixinguntil this is thoroughly worked into the mixture. This produces a masswhich is light, fluffy, and only slightly damp.

This mass or mixture is then placed in compression moulds and subjectedto a pressure of from 5 to 1 tons per square foot. Upon removal from themould, objects formed from the mass have sufiicient firmness andrigidity so that they may be lifted from the moulds and handledwithhardening is due to the action of the sodium chloride on the binder,the adhesion of the particles, and, also, by reason of the naturaltendency of perlite of the grade above specified, to knit by pressureinto a solid cake.

Under the pressures stated, dry perlite of the ,above described grademay be made to form a light cake or immobile mass as above mentioned.For the uses here concerned, however, the dry compressed cake is toofragile, and therefore the binder is used. When the binder, abovementioned, together with the setting agent, is added to this grade ofperlite aggregate, the pressure necessary to obtain a handleable objectis much less. and the insulating shapes and pipe covering sections maybe formed in a light hydraulic, or even a hand press. After forming, thecompression moulded objects may be air dried for several days at normaltemperatures, or, in the case oi insulating pipe or boiler covering, maybe applied at once and air dried in place.

The compression moulds, above mentioned, for making pipe coveringsections, consist of a semicylindrical bottom half and asemi-cylindrical upper half of smaller diameter proportioned so thatwhen pressed or forced toward and into the lower half by hydraulic ormechanical means, a semi-cylindrical shape or covering section is formedwhich has an inner face adapted to fit over one half of the pipe to becovered and mate with a similar section on the opposite side of thepipe. The thickness of these sections will vary according to the degreeof insulation desired. They made be made of any length which may beconveniently handled. After positioning, the two mating covering halvesmay be wrapped with fabric, or held by metal bands. so as to secure themto the pipe to be insulated.

As above described, I have provided a means for forming insulating pipesections by immediate compressive molding. This has been round to becheaper and to provide better insulation than compositions heretoforeused. The covering can be used to support the weight of the pipes, ifdesired.

Perlite, which is the chief ingredient of this composition, resistscompression to such an extent that once compressed it cannot be furthercompressed except by a pressure greater than that first applied. It doesnot crush to an impalpable powder as other insulating materials would dounder similar conditions. vermiculite, for example, can not becompressed either with or without a binder to obtain any fixed form orshape. If it is compressed sufiloiently to reduce its volume, only acrushed mass results. Mixtures of magnesium carbonate and asbestosfibers can not be compressed as here indicated. These materials must bemixed with water and moulded and then kiln dried, all of which includesa process which is more expensive than that above described.

Sodium silicate is used here because of the small quantity required. Itspresence does not mitigate against the insulating qualities of theperlite and it makes possible the formation of rigid shapes by pressuremoulding.

It-is also resistant to heat and does not break down or lose its bindingqualities when heated even somewhat beyond 1200 F. On the other hand,all other binders hereto-tore applied to other substances, give on watervapor and break down at a much lower temperature. Another advantags ofusing perliteof theclassand quality above stated is that it will knittogether as above explained. On the other hand, such materials as pmniceor horny brittle perlite will not knit and when compressed crumble to anunusable mass and can not be compressed in the manner above described.

Whereas I have explained one example 01' my invention, many variationswill su gest-themselves to those familiar with the art and therefore Iwish to be. limited only by the following claims.

I claim:

1. A compressible composition, for .dry pressing semi-cylindricalinsulating pipe-covering sectlons, consisting of expanded perlitegranules composed of thin walled bulbous cells adapted to knit and forma solid cake under compression, of plaster grade aggregate and having adensity of eight pounds per cubic foot, one cubic foot; a binderconsisting of sodium silicate 40 Baum, one halt gallon; and a settingagent consisting of powdered rock salt ten ounces.

2. A compressible composition for dry pressing semi-cylindricalinsulating pipe covering sections, consisting of one cubic foot ofexpanded perlite granules having a structure composed of small evenlyspaced bulbous cells, adapted to knit under compression and sized toform an aggregate of which will pass an 8 mesh screen and not more than3% of which will pass a 100 mesh screen, having a density of from 4 to10 pounds per cubic foot; sodium silicate 40 Baum, one half gallon,liquid measure; and powdered sodium chloride approximately ten ouncesavoirdupois.

3. A compressible composition for dry pressing semi-cylindricalinsulating pipe covering sections, consisting of expanded perlitegranules composed of thin walled bulbous cells adapted to knit and forma solid cake under compression. of plaster grade aggregate. having adensity of four to ten pounds per cubic foot, one cubic tools; a binderconsisting of sodium silicate iorty degrees Baum approximately one-halfgallon; and a setting agent consisting of powdered rock saltapproximately ten ounces.

4.. A compressible composition for dry pressing semi-cylindricalinsulating pipe covering sections, consisting of perlite granulescomposed of thin walled bulbous sections adapted to knitarnd form asolid cake under compressiomand having a density of approximately eightpounds per cubic foot, one cubic foot; together with a binder consistingof sodium silicate forty degrees Baum suflicient to make a light flurrymixture when said particles are evenly coated therewith; and a settingagent consisting of powdered rock salt approximately ten ounces.

HAROLD KARREN THOMAS.

REFERENCES CITED The foilo'wing references are of record in the file ofthis patent:

UNITED STATES PATENTS OTHER REFERENCES Ralston: Perlite, Source ofSynthetic Pumice. Information Circular. U. .8. Dept. of Interior, August1948.

1. A COMPRESSIBLE COMPOSITION, FOR DRY PRESSING SEMI-CYLINDRICALINSULATING PIPE COVERING SECTIONS, CONSISTING OF EXPANDED PERLITEGRANULES COMPOSED OF THIN WALLED BULBOUS CELLS ADAPTED TO KNIT AND FORMA SOLID CAKE UNDER COMPRESSION, OF PLASTER GRADE AGGREGATE AND HAVING ADENSITY OF EIGHT POUNDS PER CUBIC FOOT, ONE CUBIC FOOT; A BINDERCONSISTING OF SODIUM SILICATE 40* BAUME, ONE HALF GALLON; AND A SETTINGAGENT CONSISTING OF POWDERED ROCK SALT TEN OUNCES.